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DC (LK/SW) 125804/1© UCLES 2016 [Turn over

Cambridge International ExaminationsCambridge Ordinary Level

*6543207907*

COMPUTER SCIENCE 2210/23

Paper 2 Problem-solving and Programming October/November 2016

1 hour 45 minutes

Candidates answer on the Question Paper.

No Additional Materials are required.

No calculators allowed.

READ THESE INSTRUCTIONS FIRST

Write your Centre number, candidate number and name in the spaces at the top of this page.Write in dark blue or black pen.You may use an HB pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, glue or correction fluid.DO NOT WRITE IN ANY BARCODES.

Answer all questions.

DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.

You are advised to spend no more than 40 minutes on Section A (Question 1).

No marks will be awarded for using brand names of software packages or hardware.

At the end of the examination, fasten all your work securely together.

The number of marks is given in brackets [ ] at the end of each question or part question.

The maximum number of marks is 50.

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Section A

You are advised to spend no longer than 40 minutes answering this section.

Here is a copy of the pre-release material.

DO NOT attempt Tasks 1, 2 and 3 now.

Use the pre-release material and your experience from attempting the tasks before the examination to answer Question 1.

Pre-release Material

The headteacher of a school needs a program to record and count the votes for a class captain. Each student in the class will be allowed one vote. There can be up to 30 students in a class.

Write and test a program for the headteacher.

• Your program must include appropriate prompts for the entry of data. • Error messages and other output need to be set out clearly. • All variables, constants and other identifiers must have meaningful names.

You will need to complete these three tasks. Each task must be fully tested.

TASK 1 – Set up the voting

Each class can choose from up to four different students as candidates for their class captain. Set up a routine that allows:

• between two and four different candidate names to be input and stored• the candidate names to be displayed with a number (1, 2, 3 or 4) beside each name• a choice of 1, 2, 3 or 4 to be entered to record a vote; all other entries are rejected• up to four totals set to zero ready to record the votes• a maximum of 30 votes to be cast

TASK 2 – Record and count each vote

Input a number 1, 2, 3 or 4; add 1 to the appropriate total.

Output the name of the candidate voted for or output ‘invalid vote’ if a vote is rejected.

TASK 3 – Show the result

When all the votes have been cast, display the candidates’ names with their totals in descending order of totals. If there is a clear winner, display the candidate’s name with the words ‘NEW CLASS CAPTAIN’ beside it; otherwise display ‘NO OVERALL WINNER’.

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1 (a) All variables, constants and other identifiers should have meaningful names.

For four of the variables, constants or arrays that you used in Task 1, state the name, data structure, data type and its use.

Name 1 ......................................................................................................................................

Data structure ............................................................................................................................

Data type ...................................................................................................................................

Use ............................................................................................................................................

Name 2 ......................................................................................................................................

Data structure ............................................................................................................................

Data type ...................................................................................................................................

Use ............................................................................................................................................

Name 3 ......................................................................................................................................

Data structure ............................................................................................................................

Data type ...................................................................................................................................

Use ............................................................................................................................................

Name 4 ......................................................................................................................................

Data structure ............................................................................................................................

Data type ...................................................................................................................................

Use ........................................................................................................................................[8]

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(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements or a flowchart. You can assume that Task 1 has been completed and that there are three candidates for class captain.

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(c) Explain how you show the result (Task 3). You may include programming statements as part of your explanation.

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(d) Explain how you could extend your solution to deal with the case of ‘NO OVERALL WINNER’.

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Section B

2 Read this section of program code that:

• inputs 10 numbers • checks whether each number is within a specified range • totals the numbers within the range and outside the range

1 InRange = 0 2 OutRange = 1000 3 FOR Count = 1 TO 10 4 INPUT Num 5 IF Num > 10 AND Num < 20 THEN InRange = InRange + 1 6 ELSE OutRange = OutRange - 1 7 Count = Count + 1 8 NEXT X 9 PRINT InRange, OutRange

(a) There are four errors in this code.

Locate these errors and suggest a correction to remove each error.

Error 1 ........................................................................................................................................

Correction ..................................................................................................................................

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Error 2 ........................................................................................................................................

Correction ..................................................................................................................................

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Error 3 ........................................................................................................................................

Correction ..................................................................................................................................

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Error 4 ........................................................................................................................................

Correction ..................................................................................................................................

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(b) Decide, with reasons, whether the numbers 10 and 20 are within or outside the range.

Number Within range (✓)

Outside range (✓) Reason

10……………………………………………………………………..

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20……………………………………………………………………..

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[4]

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3 The flowchart below inputs the price of an item under $10. The change from a $10 note is output. Any amount less than 5 cents is rounded up to 5 cents.

The predefined function INT rounds a number down to the nearest whole number; for example Z ← INT(5.7) gives the value Z = 5

START

INPUT Price

IsChange>= 1?

Yes

Yes

No

No

No

Yes

Change 10 – Price

END

OUTPUT TenCents," ten cent coins"

IsChange>= 0.5?

Is Change*10 –TenCents

> 0?

Dollars INT(Change)

Change Change – 0.5

Change Change – INT(Change)

TenCents INT(Change * 10 + 0.5)

OUTPUT Dollars," dollars"

OUTPUT "One 50cent coin"

OUTPUT "One 5cent coin"

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Complete the trace table for the input data: 6.29

Price Change Dollars TenCents OUTPUT

[5]

4 Four validation checks and four descriptions are shown below.

Draw a line to link each validation check to the correct description.

Validation check Description

Presence checkNumbers between two

given values are accepted

Range checkData is of a particular

specified type

Type checkData contains an exact number of characters

Length checkEnsures that some data

have been entered

[3]

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5 REPEAT ... UNTIL and WHILE ... DO ... ENDWHILE are two different loop structures you can use when writing pseudocode.

Explain, using examples, why you would choose to use each type of loop.

Example 1 .........................................................................................................................................

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Reason for choice .............................................................................................................................

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Example 2 .........................................................................................................................................

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Reason for choice .............................................................................................................................

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6 A database, THEATRETOURS, was set up to show the tour dates, towns, number of seats and prices in local currency for a Shakespeare play.

Town Tour Date Number of Seats Price Local Currency

Wigan 18/08/2016 120 15.00

Dumfries 20/08/2016 160 12.50

Turin 25/08/2016 200 17.00

Macon 27/08/2016 75 18.00

Bordeaux 29/08/2016 170 20.00

Algiers 01/09/2016 125 1350.00

Windhoek 05/09/2016 65 90.00

Windhoek 06/09/2016 65 90.00

Port Elizabeth 10/09/2016 200 110.00

(a) Explain why none of the fields in the database can be used as a primary key.

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(b) State a field that could be added as a primary key.

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Give a reason for choosing this field.

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(c) Use the query-by-example grid below to provide a list of tour dates and seat prices in alphabetical order of town.

Field:

Table:

Sort:

Show:

Criteria:

or:

[4]

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To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series.

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